MATTHEW McConaughey has revealed how he shed over 20 kilos for his latest role.

The 43-year-old star combined exercise with a diet bordering on starvation to play a HIV patient in Dallas Buyers Club.

The usually buff actor told Access Hollywood he only ate two tiny meals a day to get down to a body weight of 60 kilos.

"I ate a lot of fish, but only five ounces of it, and then a cup of vegetables," said McConaughey.

The Magic Mike star was planning to do intense cardio workouts every day but decided to ditch his exercise regime after two weeks due to some surprising results.

"I had a week where I had an injury and I couldn't exercise, and I stayed on the same diet but I lost the same amount of weight. I was like, 'Oh, well. Let me see if I can do this without exercise.' And I lost the same amount of weight," said McConaughey.

Dallas Buyers Club, which is based on a true story, will be released in Australia in January 2014.